1. Field of the Invention
The present invention relates to a combined radial and thrust bearing.
2. Description of the Prior Art
A combined radial and thrust bearing is generally used, for example, a sliding hinging portion for opening and closing a door along the vehicle body of an automobile.
An example of a conventional combined radial and thrust bearing (see U.S. Pat. No. 3,930,692) will be explained with reference to FIGS. 5 and 6. FIG. 5 is a side elevational view thereof and FIG. 6 is a sectional view thereof shown in FIG. 5, taken along the line VI--VI.
The combined radial and thrust bearing shown in FIGS. 5 and 6 is composed of a radial rolling bearing A and a thrust rolling bearing B and supports the linear relative movement of a first member C and a second member D.
The radial rolling bearing A is composed of an outer ring 1, a plurality of rollers 2 disposed between the inner periphery of the outer bearing race 1 and the second member D, and a retainer 3 for holding the plurality of rollers 2 at regular circumferential intervals. The outer ring 1 is provided with a large-diameter cylindrical portion 4 and a small-diameter cylindrical portion 6 which has a smaller diameter than the large-diameter cylindrical portion 4 and which has several projections 5 projecting outwardly in the diametrical direction on the periphery at one end portion thereof.
The thrust rolling bearing B is composed of two races 7 and 8, a plurality of rollers 9 disposed between the races 7 and 8, and a retainer 10 for holding the plurality of rollers 9 at regular circumferential intervals. The retainer 10 for holding the rollers 9 is attached to the two races 7 and 8 inseparably therefrom. The first race 7 is composed of an annular plate portion 11 and an inner cylindrical portion 12 which is integrally provided on the inner periphery of the annular plate portion 11. At several portions on the inner periphery of the inner cylindrical portion 12 are provided notches 13 which correspond to the projections 5 of the small-diameter cylindrical portion 6, and projections 14 for preventing the retainer 10 from coming off. The second race 8 is composed of an annular plate portion 15 and an outer cylindrical portion 16 which is integrally provided on the outer periphery of the annular plate portion 15. At several portions on the outer periphery of the outer cylindrical portion 16 are provided projections 17 which project inwardly in the diametrical direction so as to prevent the holder 10 from coming off.
By fitting the inner cylindrical portion 12 of the first race 7 of the thrust rolling bearing B over the small-diameter cylindrical portion 6 of the outer ring 1 of the radial rolling bearing A, and caulking the end portion of the small-diameter cylindrical portion 6, the radial rolling bearing A and the thrust rolling bearing B are united into one body.
A combined radial thrust bearing having the above-described structure, however, has the following problems.
The small-diameter cylindrical portion 6 is caulked toward the first race 7 of the thrust rolling bearing B in order to unite the radial rolling bearing A and the thurst rolling bearing into one body. The caulking operation itself is troublesome and increases the number of assembling steps, thereby lowering the manufacturing efficiency.
Since the inner cylindrical portion 12 of the first race 7 of the thrust rolling bearing B is fitted over the small-diameter cylindrical portion 6 of the radial rolling bearing A so as to unite them into one body and the wall of the cylindrical portion 12 is overlaid on the wall of the cylindrical portion 12 in the diametrical direction, the dimensions of the outer diameter of the small-diameter cylindrical portion 6 of the radial rolling bearing A and the outer diameter of the thrust rolling bearing B are restricted to predetermined dimensions. The length in the diametrical direction of the retainer 10 for holding the thrust rollers 9 is therefore shortened by the dimension equivalent to the total wall thickness of the cylindrical portions 6 and 12, so that the length of the thrust roller 9 is also restricted. Thus, the load capacity of the thrust rolling bearing B is insufficient.
Since the width of the thrust rolling bearing B required for assembly is different depending upon the object to which the bearing B is attached, the dimension is conventionally adjusted by varying the thickness of the annular plate portion 11 of the first race 7 of the thrust rolling bearing B. However, if the thickness of the annular plate portion 11 is increased, the thickness of the inner cylindrical portion 12 which is integral with the annular plate portion 11 is also increased. The total wall thickness of the cylindrical portions 6 and 12 is therefore increased, thereby aggravating the above-described problem.